Detecting water and other volatiles



April 8, 1941. G RAGATZ 2,237,824

DETECTING WATER AND OTHER VOLATILES File d June 26, 1937 IN VEN TOR. Edward Gil-Pagafz ATTORNEY- Patented Apr. 8, 1941 UNITED STTES PTENT OFFECE DETECTING WATER AND OTHER VOLATILES Edward G. Ragatz, San Marino, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California Application June 26, 1937, Serial No. 150,657

Claims.

' The present invention relates to methods and apparatus for detecting influx of water, and more particularly pertains to a method and apparatus whereby a warning is given whenever excessive quantities of water or other low boiling liquids are present in a' relatively higher boiling liquid. Specifically, the invention is of particular importance in connection with solvent extraction operations, particularly where the solvent employed is of the type of liquid sulfur dioxide. This is due to the fact that liquid sulfur dioxide is not corrosive, while sulfurous acid which results from contact of liquid sulfur dioxide with water is corrosive, particularly when large quantities Also, in the solvent dewaxing of mineral oilas is customarily practiced, the oil to be dewaxed is mixed with a solvent, the oil-solvent mix chilled to precipitate the wax, and the precipitated wax separated by filtration, centrifuging, or cold settling from the resultant dewaxed oil. Some of the solvent employed in the process is retained in the separated slack wax, the bulk of the solvent being normally retained in the dewaxed oil. For the purpose of further utilization of the Wax, as well as to prevent loss, it is desirable to remove this solvent from the slack wax thus produced. However, if any water is :present in the system, it freezes out and is separated along with the slack wax. In such case, the recovery of solvent from the slack wax is accompanied by great difiiculties. Thus, even if the solvent used is not of the type of liquid sulfur dioxide which, as aforesaid, reacts with water to produce a corrosive acid, the presence of any appreciable quantities of water is undesirable, particularly when a solvent is employed which is miscible or soluble in water. In such case, it is extremely difficult to recover the solvent substantially free from water. On the other hand, if the water is not separated from the system it will gradually accumulate and dilute the solvent and this destroys its effectiveness as a dewaxing or solvent extracting agent.

In view of the above, the oils which are treated with solvents, whether for the purpose of separating therefrom the slack wax, or, for example, for treating a mineral oil distillate to produce fractions or components which are, respectively,

, more and less paramnic in nature than the original oil treat, are all dehydrated. However, it is impractical to remove all traces of water from such oils. Furthermore, in large plant operations it frequently occurs that a certain portion of the oil. under treatment does not receive the necessary degree of treatment, with the result that such oil may contain an unduly large amount of water which, as stated above, may cause damage to the treating plant or destroy the effectiveness of the solvent utilized. It is, therefore, the main object of the present invention to eliminate the above'disadvantages and.

to detect the presence of any appreciable quantities of water in the oil which is to undergo treatment with one or more solvents for the purpose or purposes mentioned above.

It is a further object of this invention to pro vide a process and apparatus whereby relatively small quantities of Water present in an oil to be solvent treated may be continuously and adequately removed from said oil prior to its said solvent treatment, and whereby the presence of any appreciable and/or critical quantities of such water will be immediately detected so that adequate and proper steps may be taken to prevent any and all of the above defects caused by the presence of such water during the solvent extracting or dewaxing operations.

The details of the present invention will bei come apparent from the hereinafter contained description with particular reference to the annexed drawing, the single figure of which is a diagrammatic view of an apparatus for carrying out a preferred embodiment of the invention. Referring now more particularly to this drawing, the oil to be treated is introduced continuously through line Ill into a tank I2, line I0 being equipped with a valve I3 which is actuated by a float I located in' tank l2 so that the oil in said tank is constantly maintained at a uniform and predetermined level. Line I0 is further provided with a preheater Hi, the heating medium for which enters said heater through line H and is withdrawn therefrom through line 18. The purpose of the heater will be described in detail hereinbelow in connection with the operations of the apparatus or plant. Dome 20 on tank I2 is provided with a vapor discharge line 2| which leads to a vacuum pump or compressor 22 having only a definite limited capacity. The discharge end of said pump or compressor may be open to the atmosphere or may be connected by line 23 to any other part of the plant. This phase does not constitute any portion of the present invention, and is therefore not shown.

Tank I2 is further provided with a liquid discharge line 25 which may be equipped with a constant volume pump 26 and a valve 21. tank is also provided with a vent line 29 termi nating in a device 30 which consists of an alarmor a similar mechanism which is responsive to and actuable by changes in pressure in tank I2.

The operations of the above described system are comparatively simple. Assumingthat the stock consists of a lubricating oil which-is to :be

treated with a solvent such as a mixture of liquid sulfur dioxide and benzene for. the purpose .of. resolving said oil into two components which .are,.

respectively more and less paraflinic in nature thanthe original stock ,to be treated, this oil, conveyed into line I!) from .an outside source is first preheated in heater I6 to a temperature of 225 F., andthen introduced at said temperature into tank .I2, the rate of said inflow being regulated by the float controlled valve I3, and being obviously dependent on the rate of discharge of the oil through line 25. In view of the fact that the oil is heated to the above temperature, any water which may be present in the oil will evaporate, and will separate from the oil in tank I2. The pressure in the vapor space above the liquid level in said tank is maintained at a. predetermined vacuum by the action of vaccum pump 22, the gases and vapors being withdrawn by said pump through line 2 I However, because, as stated, this pump is only of a limited capacity, said predetermined vacuum in the vapor space in tank I2 will be obtained only when the oil being introduced thereinto contains only a very small or substantially negligible percentage of water. If,however, a slug of water enters line ID together with the oil to be treated, it will vaporizeinheater I6 and will create an excessive pressure in tank I2. In such case, this excessive pressure will be transmitted through line 29 to device 30, thus producing an alarm. 7

Obviously, many modifications and variations of the invention, as hereinbefore set .forth, may be made without departing from the spirit and scope of the invention. Thus, although the specific embodiment refers to an assembly used for the detection of relatively excessive quantities of water in an oil fraction to be solvent treated, itis obvious that the same or similar apparatus may be employed to inform the operator when a relatively high boiling point liquid contains an excessive percentage of a relatively lower boiling point liquid. Also, instead of merely producing an audible or visible alarm, the structure may be adapted to operate automatically so that the system may be closed when the above described undesirable condition occurs. For this purpose, it is but necessary to provide conventional relays which will close pumps 22 and 26 (as well as the means introducing the feed into line III) as soon as the pressure in the upper part of tank I2 has reached a predetermined maximum.

It is also clear that the temperatures and pres- Thesures described above may be varied within a wide range. Thus, although the specific example given hereinabove shows that the liquid is preheated to a temperature of about 225 F., it is obvious that this temperature may be lower or higher so long as the water in the oil is vaporized. Obviously, if the low boiling substance in the liquid has a different boilingpoint or range from that of water, the degree of heating may be varied accordingly. As to the pressure in the vacuum tank I2, as well as the pressure differential which will actuate alarm 30, these may be regulated at will toobtain the desired results enumerated and described above.

It is thereforeio-be understood that the invention is notto be limited by any detail or details, except asdeiined by the following claims.

I. claim:

1. .In. a method for detecting the presence of excessive quantities of a relatively lower boiling liquid in a relatively higher'boiling llquid the steps of heating said liquid mixture to atem perature at which the lower boiling liquid evapoe rates, introducing said mixture into a. zone wherein said lower boilingliquid is separated .as. a vapor, and continuously Withdrawing said vapor from said zone at a predetermined rate whereby the presence of excessive quantities of. said vapors will cause a rise in the pressurein said zone, the pressure rise due to increased;

vaporization being utilized to actuate -warning...

' actuate warning means.

3. In a process according to claim .2 wherein. the high boiling point liquid is continuouslywitm drawn from the zone. at a predeterminedrate.

4. In a method for detecting the presence ofan excessive quantity of water in an oil fraction and.

for thetremoval of relatively small quantities of said water from said oil; the steps of heatingv the oil-water mixture. above the boiling point of the. water but insufliciently to evaporate the oil frac-. tion, continuously introducing said heated mix:- ture into a. separating zonewherein the evolved steam is caused to be separated fromtheofl. and applying a partial vacuum in said zone by, the withdrawal of said steam. at a predetermined limited rate whereby, the presence of excessive quantities of said steam will cause arise in.the pressure in said zone, and jutilizing the pressure rise due to increased steam formation to actuate warning means.

5. In a process accordingto claim 4 wherein the dehydrated oil is continuously withdrawn from the separating zone. at a predetermined limited rate.

EDWARDG. RAGATZ; 

